NEWS-e forecasts have regularly produced accurate forecasts of low-level rotation well in advance (>30 min) of tornado development for discrete supercells within highly favorable tornado environments. However, less is known about NEWS-e forecast performance in more marginal environments typical of cool season tornadoes in the southeastern U.S. This study examines NEWS-e thunderstorm rotation forecasts for four cool season events in 2015-2016, including for VORTEX-SE intensive operating periods on 31 March and 29 April 2016.
Each NEWS-e low-level vertical vorticity and updraft helicity forecast is verified against Multi-Radar Multi-Sensor azimuthal wind shear values from the WSR-88D network using an object-based approach. Additionally, the upstream environment of each forecast rotation object will be extracted from NEWS-e. This approach allows both storm-scale (e.g. storm size, cold pool interaction) and mesoscale (e.g. conditional instability, vertical wind shear) impacts on forecast accuracy to be assessed across the four cases.